Dispensers for epoxy-type adhesives including two distinct compartments in a single cartridge body, such as that shown in U.S. Pat. No. 3,828,980, are currently available. Such dispensers permit the precise metering of two viscous adhesive components onto a discrete work surface. While such dispensers currently available do provide a convenient and reliable metering of such component adhesives, they have heretofore required a two-part plunger consisting of the plunger shaft, configured to have certain structural capabilities, and a seal cap, of a material dissimilar from the shaft and designed to have certain sealing capabilities. Since the use of such a dispenser is generally for consumers' home repair or industrial use, it must be of a rugged and reliable configuration. Thus, the structural characteristics of the plunger shaft could not heretofore be configured to provide the necessary sealing characteristics. The use of such two-part plungers has proven to be costly due to material costs and production time.
While certain modifications to the dispenser described above have been made to provide a unitary construction of a pair of parallel plunger shafts to be accommodated within a unitary cartridge including a pair of parallel compartments, such modifications still require the placement of discrete seal members at the extremity of each plunger shaft.
Accordingly, it is a primary object of this invention to provide a dispenser for metering fluids which minimizes the number of parts used in such a unit.
A more specific object of this invention is the provision of a plunger member in a dispenser which includes integrally formed seal means at the piston head, therefore eliminating separate seal elements.
Still a further object of the invention is to provide a plunger for use in a plurality of chambers simultaneously and more particularly a plunger for use with viscous materials which include an integral double lipped seal at the piston head.
In general, these objects are obtained by the dispenser of the present invention which consists of two parts, namely a cartridge having two or more cylindrical compartments and a piston or plunger unit which includes a corresponding number of piston shafts integrally joined at the top and including particularly configured seal rings unitarily configured at the opposite extremity of the shafts.
The seal region of each shaft includes a pair of axially spaced seal rings having sharp edges at their outer periphery. The outer peripheral region of each seal ring includes a frustoconical surface with the frustoconical surface of the ring nearest the extremity tapering backwardly from the extremity while the frustoconical surface of the rearward ring tapers forwardly toward the extremity. The forward ring is further configured to include a step-like surface resulting from an inner, shallow, frustoconical surface being connected to the outer surface by a short cylindrical surface. The particular elements making up the unitary configuration of the piston shafts and the advantages of these features will become apparent from the following description when read in conjunction with the accompanying drawings.